I need help with this simple indicator.

Thank you for having a look, but i don't get errors and i use all the arrays as  buffers.

Only the 3d one and i have set it as buffer.

   for(i=0; i<rates_total-main_period; i--)
   {
      signal[i] =  NormalizeDouble(iMAOnArray(main, 0, signal_period, 0, MODE_LWMA, i),6);
   }

Thanks again GumRai.

Although you are right this thing isn't working.

I really think it has to do, somehow, with the iMAOnarray() function and the latest update of MT4.

Cause it was working properly but after a recompilation stop working properly.

The key word is properly. No errors, no nothing.

It is still working but the data that it returns are false.

Have a look at the previous one.

They are almost identical. The small changes came from my tries to repair it, just like the i-- that i forgot to reverse it back again to i++ :) .

#property copyright "Konstantinos Maleas"
#property link      ""
#property version   "1.00"
#property strict

#property indicator_separate_window
#property indicator_buffers 1
#property indicator_color1 Green

   ///--- input parameter
  extern int scen = 0;
         int main_period = 12;
  extern int signal_period = 3;

   ///--- buffers
   double main[100000], signal[100000], dif[1000];


int OnInit()
{
   string short_name, short_name1, short_name2, short_name3;

   impulse_ma_period(scen,ChartPeriod());
   
  ///--- indicator line
   SetIndexStyle(0,DRAW_LINE,EMPTY,2,clrGreen);
   SetIndexBuffer(0,dif);
   
  ///--- name for DataWindow and indicator subwindow label
   short_name1 = "Dif ("+main_period+")";
   
   IndicatorShortName(short_name1);
   SetIndexLabel(0,short_name1);
  
  /////--- check for input parameter
   if(main_period<=0)
   {
      Print("Wrong input parameter Momentum Period = ",main_period);
      return(INIT_FAILED);
   }

   SetIndexDrawBegin(0,main_period);
   SetIndexDrawBegin(1,signal_period);

   return(INIT_SUCCEEDED);
}

int OnCalculate(const int rates_total,
                const int prev_calculated,
                const datetime &time[],
                const double &open[],
                const double &high[],
                const double &low[],
                const double &close[],
                const long &tick_volume[],
                const long &volume[],
                const int &spread[])
{
   int i,limit, pos = main_period;

   ////--- check for bars count and input parameter
   if(rates_total<=main_period || signal_period<=0)
      return(0);
   ///--- counting from 0 to rates_total
   ArraySetAsSeries(main,true);
   ArraySetAsSeries(signal,true);
   ArraySetAsSeries(dif,true);
   
   ///--- initial zero
   if(prev_calculated<=0)
   {
      for(i=0; i<main_period; i++)
         main[i]=0.0;
      limit=main_period;
   }
   else
      limit=prev_calculated-1;
      
   for(i=0; i<rates_total; i++)
   {
     main[i] =  NormalizeDouble(iMA(Symbol(),0,main_period,0,MODE_LWMA,PRICE_MEDIAN,i),6);
   }
   
   for(i=0; i<rates_total; i++)
   {
      signal[i] =  NormalizeDouble(iMAOnArray(main, 0, signal_period, 0, MODE_LWMA, i),6);
   }
   
   for(i=0; i<rates_total; i++)
   {
      dif[i] = NormalizeDouble((main[i] - signal[i]) * 1000,6);
   }
   return(rates_total);
}

///----- Moving Average Installation -----------------------------------------------------------------------------------------------
int impulse_ma_period(int ma_imp, int tf)
{
   if ( ma_imp == 0 )
      switch(tf)
      {
         case 1 :  main_period = 15; break;
         case 5 :  main_period = 12; break;
         case 15 :  main_period = 16; break;
         case 30 :  main_period = 12; break;
         case 60 :  main_period = 12; break;
         case 240 :  main_period = 15; break;
         case 1440 :  main_period = 22; break;
         case 10080 :  main_period = 13; break;
         case 43200 :  main_period = 12; break;
      }
   if ( ma_imp == 1 )
      switch(tf)
      {
         case 1 :  main_period = 10; break;
         case 5 :  main_period = 8; break;
         case 15 :  main_period = 11; break;
         case 30 :  main_period = 8; break;
         case 60 :  main_period = 8; break;
         case 240 :  main_period = 10; break;
         case 1440 :  main_period = 15; break;
         case 10080 :  main_period = 9; break;
         case 43200 :  main_period = 8; break;
      }
   if ( ma_imp == 2 )
      switch(tf)
      {
         case 1 :  main_period = 7; break;
         case 5 :  main_period = 6; break;
         case 15 :  main_period = 8; break;
         case 30 :  main_period = 6; break;
         case 60 :  main_period = 6; break;
         case 240 :  main_period = 7; break;
         case 1440 :  main_period = 6; break;
         case 10080 :  main_period = 7; break;
         case 43200 :  main_period = 7; break;
      }
   if ( ma_imp == 3 )
      switch(tf)
      {
         case 1 :  main_period = 5; break;
         case 5 :  main_period = 4; break;
         case 15 :  main_period = 5; break;
         case 30 :  main_period = 4; break;
         case 60 :  main_period = 4; break;
         case 240 :  main_period = 5; break;
         case 1440 :  main_period = 5; break;
         case 10080 :  main_period = 4; break;
         case 43200 :  main_period = 4; break;
      }
   if ( ma_imp >= 4 )
      switch(tf)
      {
         case 1 :  main_period = 3; break;
         case 5 :  main_period = 2; break;
         case 15 :  main_period = 3; break;
         case 30 :  main_period = 2; break;
         case 60 :  main_period = 2; break;
         case 240 :  main_period = 3; break;
         case 1440 :  main_period = 3; break;
         case 10080 :  main_period = 3; break;
         case 43200 :  main_period = 2; break;
      }
   return(main_period);
}

   ///--- buffers
   double main[100000], signal[100000], dif[1000];

   ///--- counting from 0 to rates_total
   ArraySetAsSeries(main,true);
   ArraySetAsSeries(signal,true);
   ArraySetAsSeries(dif,true);

The AS_SERIES flag can't be set for multi-dimensional arrays or static arrays (arrays, whose size in square brackets is preset already on the compilation stage).  ;)